Light detection and ranging ("lidar") which comprises a laser generator transmitting signals in a given direction and a receiver receiving these signals after partial backscattering by the atmosphere is already in use for measuring some of these parameters. The received signals are then analyzed as a function of time and of wavelength, to determine cloud altitude or wind speed.
Prior "lidar" systems are generally specialized and designed to measure one or a few particular parameters. When it is necessary to know not only the variations as a function of time in the intensity of the received signal but also the doppler shift between the transmitted signal and the received signal, or variations in the spectrum width of the signal, it is necessary either to use a plurality of laser generators, or else a plurality of receivers, and it may be necessary to implement models of other physical parameters in order to obtain the looked-for parameter(s).
This increases the cost of such systems and also gives rise to considerable complexity in signal processing.
A particular object of the invention is to avoid these drawbacks.
An object of the invention is to provide apparatus enabling a large number of meteorological parameters to be measured using a single laser generator in association with a single receiver.
Another object of the invention is to provide apparatus of this type enabling the looked-for parameters to be obtained directly merely by analyzing the signals sequentially.